PfCSP-specific CD4 ⁺ T cells target three N-CSP and three C-CSP epitopes. Transgenic CD4⁺ Jurkat76 T cell lines expressing TCRs from T cells with an activated phenotype after stimulation of PBMCs with N- or C-CSP peptide pools (donors F3, F4, F7, and F9) were generated. (A) IL-2 concentrations as quantified by ELISA in supernatants of T cell lines (n = 66) co-cultured with autologous B cells pulsed with N-CSP or C-CSP peptide pools or with non-peptide–pulsed autologous B cells (unstim). Color coded by specificity (gray: non-CSP specific, turquoise: N-CSP specific, and orange: C-CSP specific). (B) Frequency of N- and C-CSP–reactive and nonreactive TCRs. (C) IL-2 concentrations as quantified by ELISA in supernatants of T cell lines co-cultured with autologous B cells pulsed with the indicated peptides (+) or left unstimulated (−). n indicates the number of tested T cell lines. (D) Schematic map of the identified target epitopes and aa positions within PfCSP. Sequence diversity of TCR epitopes among 481 PfCSP sequences isolated from seven geographic regions published by Tanabe et al. (2013), and polymorphic aas are highlighted in red. (E)TRAV and TRBV usage and number of individual TCRs with the indicated epitope specificity. (F) Number of epitope-specific TCRs among all cloned and tested TCRs with the indicated V segments. (A–C, E, and F) Data from one out of two independent experiments are shown.